Skeletal Muscle Structure Flashcards
If you have more glycogen you will haven more water. T/F
True
Glycogen provides what?
In muscle to provide carbs for energy
Fat in muscle cells is good for endurance? T/F
True
How much muscle mass is lost until it’s deathly?
30%
Surgery creates a catabolic situation. Loses muscle mass. T/F
True
Skeletal Muscle Organization
Whole muscle (belly) Muscle fascicle (bundle of m.fibers) M.fibers (muscle cell) Myofibril (sarcomeres in series) Sarcomere (Z-disc to Z-disc) Myofilament (actin and myosin)
Sarcomere
Z line to Z line
Thin - actin
Thick - myosin
Costamere
Attaches myofibril to sarcolemma
Comes off z-line and goes lateral to muscle line of pull, pulls on costamere then sarcolemma
Costamere transmits which direction?
Lateral, parallel
There are different types of costameres (3)
What happens if you get a disruption of one protein?
Can cause muscle problems in patients! Entire muscle can get scarred!
Intermediate filaments
Around myofibrils and hold them in place
Titan
Largest molecule of protein in muscle
PEVK domain - important
Helps keep the thick filament centered between 2 Z-lines during contraction, believed to control the # of myosin molecules contained in the thick filament
As sarcomere lengthens passive tension increases.
What provides passive tension in muscles?
PEVK titan
Titan
Large molecule that’s wound up (protein), expands and provides higher tension and contributes to force of muscle specifically eccentric of muscles.
What combines to Troponin C for myosin to move and bind to actin? Tropomyosin to move and expose site.
4 Ca++
Troponin T binds to
Tropomyosin
Troponin I binds to
G-actin
ATPase is responsible for
Breaking down ATP
Why are there lots of actin surrounding myosin?
So when it opens it can easily attach
M line
Strength & integrity of muscle fiber
Stabilizes thick-filament lattice
Thicker in Type 1 - high fatigue resistance, faster contracting, postural, holds up longer overtime, slow oxidative)
What creates an AP in motor neuron?
Alpha-neuron
What does Ca++ do for muscle contraction?
Binds to troponin C and get action…
The opening of Ca++ channels causes vesicles emptying of ACh into synaptic cleft
What causes the diffusion of post-synapse and combines w ACh receptor R?
Na+ and K+ permeability, depolarization of muscle cells
THe DHP channel is connected to what receptor in the SR that causes Ca++?
Ryanodine
The reason for lack of production in muscle
Disruption in DHP/Ryanodine receptors, reduced number of junctions in older adults.
E-C coupling
Conversion of electrochemical energy into mechanical energy
Men and women both produce 4-6pM on one myosin head. T/F
True
What is the one difference men vs women at the molecular level?
Testosterone levels
What makes a triad?
T-tubule lined by two sarcoplasmic reticula
Too much Ca++ released can cause
Twitch and tetanic tension
Too much can have muscle damage
Once ca gets in how fast does Ca need to get removed?
Fast! Back into SR.
Calmodulin
Parvalbumin
Calquestrin
Can lead to fatigue/cramping if Ca++ doesn’t get back to SR fast enough
ATP is needed for
Myosin and actin release
Winding Filament
Titan involved in twists at end of actin for shortening and passive tension
Optimal length of sarcomere
2.0-2.2 micrometers!
Too much overlap or not enough overlap causes lost of force production. T/F
True
